Necessary Spares?

The time saving tricks thread got me thinking. What are some items you guys carry on the trailer as far as spare parts that are relatively common and may be needed. I did a search but didn't find too much. Thanks in advance.

I carry a complete set of belts for my Choppers, a V and a Flat idler pulley, a set of connector chain links for the lift and a spare front tire in my diamond plated truck tool box. I also carry an extra 2 sets of blades, an air tank, extra two cycle mix, a roll of trimmer string and a grease gun. I'm probably missing something here, but I try to be prepared.

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^One of the lawns we mow

A helper in a glass booth ,with a little hammer chained to it for emergencies. But really, besides tools I carry hitch pins, wire ties, oil, hearing protection, glasses, fuses, assorted nuts and bolts and spare blades. If I have a small part break, I'll buy 2 of them and keep one as a spare for next time. I also installed a fire extinguisher on the trailer opposite the gas cans.